Tarnishing Mechanism Of The IP18K Rose Gold Thin Film And Deposition Of Transparent Ceramic Film By PVD

Ion plating (IP)18K rose gold coating has become more and more popular in thedecorative market sector. But because of easily discoloring and scratching, its ornamentquality will be greatly reduced. It’s an important R&D direction to improve the wear andcorrosion resistance of the rose gold layer without degrading its shiny appearance.Scanning Electron Microscope(SEM),X-Ray Photoelectron Spectroscopy(XPS) andX-Ray diffraction(XRD) are used to study the discoloration mechanism of IP rose goldcoating. It’s found that the tarnished zone is usually caused by dark red Cu2O corrosionreaction product.The transparent Al2O3film on the304stainless steel was deposited by reactive twinmagnetron sputter with or without anode ion source. Optical performances of those coatingswere characterized by CM-2300D color tester, UV-3101PC spectrum differential instrument.Also, the corrosion resistance and wear resistance of these coatings were measured andanalyzed. The following conclusion can be made.1. As far as the transmittance and appearance color difference of the Al2O3film deposited byreactive twin magnetron sputter is concerned, the coating duration and relatively lessimportance. Oxygen flow rate has a greater impact on the deposition rate and opticalproperties of the Al2O3film.2. When the transparent Al2O3film is deposited onto the polished stainless steel surface,obvious optical interference will appear after the coating thickness is above a certain value. Inthis paper, the critical thickness of the Al2O3film-1prepared by reactive sputtering is86nm,the critical thickness of the dense Al2O3film-2prepared by anode ion source is80nm, whilethe critical thickness of the bilayer structure Al2O3film-3is about105nm. The criticalinterference thickness of a bilayer Al2O3film-3can be improved by about20%than that of adense Al2O3film-2.3. After24h vibration grinding experiments, the weight loss of a uncoated304stainless steelsample is2.10mg, and it is1.21mg for a304steel sample covered by the Al2O3thin film-1,1.06mg for those samples coated by a Al2O3dense thin film-2,1.10mgfor those samples coated by bilayer structure Al2O3thin film-3.The surface grinding marks ofthe uncoated304stainless steel sample are dense,coarse and deep groove, while the abrasivegrooves of those samples coated by a thin transparent Al2O3thin film appear short andshallow.4. The corrosion current density of the uncoated304stainless steel is3.66×10-4mA/cm2; it is9.76×10-5mA/cm2for a304steel sample covered by the Al2O3thin film-1, and1.281×10-5mA/cm2for those samples coated by a Al2O3dense thin film-2, and2.261×10-5mA/cm2forthose samples coated by bilayer structure Al2O3thin film-3. Apparently, the corrosionresistance of the304stainless steel can be enhanced by almost one order by magnetronsputter deposition of transparent Al2O3film under the aid of an ion source.